Human Biology and Health
Chapter 1
Bones, Muscles, and Skin
Section 1- Body Organization and Homeostasis (pages 6-11)
I. Levels of Organization
A. Cells – basic units of structure and function in a living
thing.
1. Structures of cells
a. Cell membrane – forms the outside boundary of the
cell.
b. Nucleus –directs cell’s activities. Important in
reproduction of cells
c. Cytoplasm – clear, jellylike substance with many
cell structures called organelles.
2. Functions of cells –
a. digestion/metabolism
b. growing and reproduction
c. excretion
B. Tissues – a group of similar cells that perform the same
function
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1. Muscle – can contract or shorten for body movement.
2. Nervous – directs the process of movement by passing
electrical messages between brain and body parts.
3. Connective – provides support and connection.
a. bone
b. fat
4. Epithelial – covers inside and outside surface of the
body for protection.
C. Organs and organ systems
1. Organ – a structure that is composed of different kinds
of tissue and performs a specific function
2. Organ system – a group of organs that work together to
perform a major function
I.
Homeostasis – the process by which the organism’s internal
environment is kept stable in spite of changes in the external
environment.
A. Homeostasis in action – Constant internal human body
temperature at 37ºC /98.6ºF, only varies when sick.
B. Maintaining homeostasis
1. sweating – cools body
2. shivering – produces heat to keep warm
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3. stress can throw off homeostasis
C. Stress and homeostasis
1. stress – reaction of the body to potential threats,
challenges and disturbing events.
2. Bike example – pg. 11
Section 2 – The Skeletal System (pages 12-19)
I.
What the skeletal system does – the framework made up of
all the bones is the skeleton.
 Adults have about 206 bones. Babies have 275 and then
they fuse during development.
A. The five major functions of the skeletal system
1. Shape and Support
a. backbone (vertebral column) is the center of the
skeleton.
b. Vertebrae (singular: vertebra) - 26 small bones that
make up the backbone.
2. Movement – Muscles pulls on the bones to make
movement
3. Organ Protection- ex. Skull protects the brain
4. Blood Cell Production – Arm and leg bones make
certain blood cells.
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5. Storage of Minerals and other materials- Bones store
minerals such as Calcium & Phosphorus and released
when needed.
II.
Joints of the Skeleton where two bones come together to
allow movement
A. Immovable Joints – skull bone
B. Moveable Joints
1. Ligaments – strong connective tissue
2. Cartilage – connective tissue that is more flexible than
bone to reduce friction.
3. A fluid lubricates the ends of the bones allowing them
to move smoothly.
III.
Bones - Strong and Living – Complex living structures which
undergo growth and development.
A. Bone Structure
1. Outer Membrane
a. covers all bones except the ends
b. thin and tough
c. blood vessels and nerves enter and leave bone
2. Compact Bone
a. Beneath the outer membrane
b. Hard and dense but not solid
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c. Small canals run through carrying blood vessels and
nerves from bone surface to living cells
3. Spongy Bone
a. small spaces
b. lightweight and strong
c. found at the end of the bone
4. Marrow – soft connective tissue found in the spaces of
the bone.
a. red – produces some of the blood
b. yellow – stores the fat for energy.
c. Red marrow decreases production through
development.
B. Bone Strength – Strong (because of minerals P& Ca) and
lightweight
C. Bone Growth - Continued growth into adulthood
1. made during activity
2. made after accident
D. Bone Development - Some cartilage is replaced by hard
bone tissue.
IV. Taking Care of Your Bones
A. Diet – well-balanced diet including Calcium &
Phosphorus
B. Exercise – helps bones grow stronger and denser
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C. Osteoporosis – a condition in which the body’s bones
become weak and break easily due to mineral loss.
1. More common in women than men
2. Regular exercise can prevent it.
3. Calcium-rich diet can prevent it.
4. Take your vitamins!!!!
Section 3 Diagnosing Bone and Joint Injuries (pages 20-23)
I. Common Skeleton System Injuries
A. Three Common Skeleton Injuries
1. Fracture – a break in the bone
a. Simple – bone may be cracked or broken into two or
more pieces.
b. Compound – Broken ends stick out from the skin.
2. Dislocation – bone comes out of joint
3.Sprain – ligaments stretch too far and tear in places
II.
Identifying Injuries
A. X-rays – a form of energy that travels in waves
1. passes through soft tissue but not bone.
2. can damage your body cells, use a lead apron for
protection
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B. MRI – Magnetic Resonance Imaging
1. takes clear images of bone and soft tissues
2. analyzes vibration patterns of atoms
3. does not damage cells
4. more costly
I.
Treating Injuries
A. Cast
B. Joint replacement
1. Replace joint with artificial joint made of plastic of
metal.
2. Arthritis – disease of joints that sometimes requires
replacement
3. Arthroscopy – Through a small incision a camera is
inserted to make necessary repairs.
Section 4 The Muscular System (pages 24-29)
I.
Types of Muscles
a. Involuntary – not under your conscious control
b. Voluntary-under your conscious control
A. Skeletal Muscle (striated muscle – a word meaning banded
due to its appearance)
1. tendon –connective tissue attaches muscle to
bone
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2. voluntary muscles that react quickly and tire quickly
B. Smooth Muscle – involuntary muscles on the inside of many
internal organs; work automatically to control a variety of movements inside the body (ex. digestion)
1. not striated
2. react more slowly and tire more slowly than skeletal
C. Cardiac Muscle – involuntary muscle found in your heart
1. striated
2. does not get tired, can contract repeatedly (heartbeats)
II.
Muscles at Work
A. Muscles must work in pairs –one muscle contracts, the other
relaxes to its original length; muscles NEVER extend
B. Muscular strength and flexibility
1. exercise makes muscle cells grow wider and thicker
2. thicker muscle = stronger muscle
3. more flexible when you stretch and warm-up before exercise
Section 5 – The Skin (pages 30-35)
I.
The Body’s Tough Covering
*Largest organ in the body – stretched flat it would cover 1.5
square meters, the size of a twin mattress
A. Functions of the Skin
1. Protecting the Body
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a. Forms a barrier that keeps disease-causing organisms
outside the body
b. Helps prevents loss of important fluids such as water
2. Maintaining Temperature
a. When you're hot, blood vessels enlarge thus increasing
blood flow; heat leaves the body to cool it
b. Sweat glands produce perspiration that evaporates from
Your skin, cooling your body
B. Eliminating Wastes – perspiration eliminates waste through the
skin
C. Gathering Information – the nerves in the skin sense pressure,
pain, and temperature
D. Producing Vitamin D
1. Skin cells produce Vitamin D in the presence of sunlight
(10 minutes a day)
2. it aids digestive cells by absorbing calcium
II.
Skin is organized into two main layers
A. Epidermis – outer layer of the skin with no nerves or blood
vessels
1. Epidermis Structure– cells reproduce, mature,die and are
shed every two weeks
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2. Epidermis Function
a. dead cells protect by cushioning fingertips body
parts
b. when dead cells are shed they carry away bacteria and
other substances that settle on the skin.
c. some cells produce hard fingernails to protect, scratch and
pick up object
d. other cells produce melanin
1) a pigment gives skin its color
2) helps protect skin from burning
3) more exposure to sunlight, more melanin produced
4) more melanin yields darker skin
B. The Dermis – inner layer of the skin, contains nerves, blood
vessels, sweat glands, hairs, and oil glands
1. Dermis structures
a. Sweat glands – produce perspiration
b. Pores – openings in skin surface through which
perspiration leaves the body
c. Follicles – structure from which hair grows
2. Dermis Function
a. oil produced in glands around follicles
b. helps keep it moist
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III.
Caring for your skin
A. Healthful diet – provides energy and raw materials needed for
growth and replacement of hair, nails, and skin cells
B. Keeping skin clean – wash your skin to control oiliness and
prevent the growth of bacteria
C. Limiting Sun Exposure
1. avoid repeated exposure especially during strong sunlight
hours (10 A.M. to 2 P.M.)
2. protect skin by wearing hat, sunglasses, sunscreen (strong
SPF), and clothing with tightly woven fabric
3. Prevent damaging skin cells – possibly cancer (a disease by
which some body cells divide uncontrollably)
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